Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 159B, § 18

No driver shall operate any motor vehicle used for the transportation of property on the ways within the commonwealth, and no owner, lessee or other person having control of any such vehicle shall require or permit any driver so to operate the same, at any time after the driver has been continuously on duty for twelve hours and before he shall have had at least eight consecutive hours off duty, or at any time after the driver has been on duty sixteen hours in the aggregate in any twenty-four hour period and before he shall have had ten consecutive hours off duty.  Periods of release from duty herein required shall be given at such place and under such circumstances that rest and relaxation from the strain of the duties of the employment may be obtained.  No period off duty shall be deemed to break the continuity of duty unless it be for at least three consecutive hours at a place where there is opportunity for a rest.  In case of flood, storm or other unforeseen emergency, the driver may complete his run or tour of duty if such run or tour of duty would reasonably have been completed without a violation of this section, except for the delay caused by such emergency, or may make deliveries of necessaries of life notwithstanding the foregoing provisions of this section.  The department may make such rules and regulations as it deems necessary or advisable to insure proper enforcement of this section.